Nanometer-sized devices, such as grid polarizers, can be limited in performance by the distance between adjacent features, or the pitch of one feature to the next. For example, for effective polarization of electromagnetic radiation, the pitch in a grid polarizer should be less than half the wavelength of the electromagnetic radiation. Grid polarizers, with pitch smaller than half the wavelength of visible light, have been demonstrated. See for example U.S. Pat. Nos. 6,208,463; 6,122,103; and 6,243,199. For higher polarization contrast and to allow polarization of smaller wavelengths, such as for polarization of ultra-violet light and x-rays, smaller pitches are needed. Various methods have been proposed to solve this problem. See for example U.S. Pat. No. 7,692,860 and U.S. Publication numbers 2009/0041971 and 2009/0053655.
A desirable feature of grid polarizers is to polarize a broad spectrum of electromagnetic radiation with a single polarizer. Grid polarizers are typically formed with ribs that are the same height. It would be beneficial to form grid polarizers with variable rib height in order to allow tuning of the grid polarizer for multiple wavelengths and to allow for a smoother Ts curve. Methods have been proposed for grid polarizers with different height ribs. See for example U.S. Publication numbers 20080037101 and 20080038467.
Grid polarizers are typically formed with ribs that are situated along a single plane. It would be beneficial to form grid polarizers with ribs situated at multiple planes (i.e. multiple elevational heights in relation to a surface of the substrate). A grid polarizer with ribs that are situated along multiple planes may be tuned to multiple wavelengths and may allow for a smoother Ts curve. See for example U.S. Publication numbers 20080037101 and 20080038467.
Grid polarizers are typically formed with ribs that are all comprised of single materials.